A rabbi I know told me that he heard a mekubal, or a person educated in Kabbalah, talking, and the mekubal was using a lot of serious bad words. He approached the mekubal and asked him, "As a person so connected to God, how can you curse like that?" The mekubal replied, "Do you want to hear a real curse?" The answer was obviously no, and he got away from the mekubal as fast as he could.
Honestly, I agree with this rabbi: I really don't understand how a mekubal could speak like that. A mekubal is a person who has seriously dedicated their life to studying Kabbalah (not like Madonna), and therefore to becoming closer to God. (A real curse from a mekubal would have seriously bad effects. If you ever hear one using bad words, I beg of you, do not approach them about it.) I have published extensively on how using bad words keeps a person grounded, and keeps them from reaching a spiritual plane. Whether a person is Jewish, Christian, Muslim, or a member of any other religion, I think they want to a reach a higher level: how can they curse and hold themselves back?